Best practices and other educational materials to prevent scuba diving impact in the Mediterranean Sea

The need to preserve the integrity of the seabed and its biodiversity (Descriptors 1 and 6 of the Marine Strategy Framework Directive, 2008/56/EC) makes it essential to identify the key factors to prevent damage resulting from recreational scuba diving. The main objective of this study is to provide attractive and user-friendly best practices and other visual resources (slides, infographics, video clips) to be shared among dive leaders to increase divers' awareness towards marine environment and to encourage environmentally responsible diving behavior. The proposed tools were created after a careful review of 29 scientific articles on the impact of diving in the Mediterranean Sea which allowed us to i) understand if, why and how underwater activities can represent a threat to underwater landscapes, and therefore to ii) highlight the combination of factors most likely to lead to harm, including the vulnerability of the organisms, the physical characteristics of the dive site, and the behavior and physiological conditions of the divers. Furthermore, a map was produced using a spatial indices approach based on dive pressure and site vulnerability to identify priority areas that urgently require the implementation of an efficient pre-dive briefing. To verify the effectiveness of the proposed educational material, during the summer of 2023 the underwater behavior of two groups of divers (trained vs. untrained, 218 and 576 records respectively) was monitored at the Tremiti Islands MPA in collaboration with the Laboratorio del MA.RE. S.r.l.s. Each diver was identified by a tag placed on the tank and by a nickname to guarantee their anonymity. Interactions between divers and the environment included simple contact with the substrate (82%), disturbance/damage to living organisms (1.7%), and resuspension of sediment (16%). Untrained divers touched the seabed more often than trained divers, especially when using a camera, regardless of their certification level. The proposed material could be used during pre- and post- dive briefings, for educational or training activities aimed at recreational, technical, and scientific divers alike, as well as marine citizen scientists.